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Bergfelt, Andreas
Publications (6 of 6) Show all publications
Bergfelt, A., Mogensen, R., Lacey, M., Guiomar, H., Brandell, D. & Bowden, T. (2018). Mechanically Robust and Highly Conductive Di-Block Copolymers as Solid Polymer Electrolytes for Room Temperature Li-ion Batteries. In: : . Paper presented at 16th International Symposium on Polymer Electrolytes (ISPE-16).
Open this publication in new window or tab >>Mechanically Robust and Highly Conductive Di-Block Copolymers as Solid Polymer Electrolytes for Room Temperature Li-ion Batteries
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Alternative solid polymer electrolytes (SPEs) hosts to the archetype poly(ethylene oxide) are gaining attention thanks to their appealing properties, such as higher cation transport number, thermal stability and electrochemical stability [1]. In addition, high mechanical stability is required in order to integrate easy-to-use materials into flexible or ‘structural’ batteries [2, 3].

 In this work, a solid polymer electrolyte (SPE) featuring high ionic conductivity and mechanical robustness at room temperature is presented. The SPE consists of a di-block copolymer, poly(benzyl methacrylate)-poly(ε-caprolactone-r-trimethylene carbonate) (BCT), mixed with different loadings of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The highest ionic conductivity achieved for these SPEs was found with 16.7 wt% LiTFSI loading (BCT17), reaching 9.1 x 10-6 S cm-1 at 30 °C. The limited current fraction (F+) for the BCT17 electrolyte was calculated to be 0.64 with the Bruce-Vincent method. Furthermore, dynamic mechanical analysis showed a storage modulus (E’) of 0.2 GPa below 40 °C and 1 MPa above 50 °C. These results indicate that BCT with LiTFSI is a competitive electrolyte, combining high ionic conductivity and modulus at ambient temperatures.

 LiFePO4|BCT17|Li half-cells showed good cycling performance at 60 °C. At 30 °C, where the SPE possessed significantly higher modulus, decent cell performance could still be achieved after several optimization steps. These included incorporating a SPE as binder, and infiltration cast the SPE on the electrode to maximize the contact between both components, thereby improving the interfacial contact and decreasing the cell resistance and overpotential when cycling the battery device.

 References

[1] J. Mindemark, M.J. Lacey, T. Bowden, D. Brandell. Prog Polym Sci, (2018). DOI: 10.1016/j.progpolymsci.2017.12.004.

[2] J.F. Snyder, R.H. Carter, E.D. Wetzel. Chem Mater, 19 (2007) 3793-801.

[3] W.S. Young, W.F. Kuan, Thomas H. Epps. J Polym Sci, Part B: Polym Phys, 52 (2014) 1-16.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-374680 (URN)
Conference
16th International Symposium on Polymer Electrolytes (ISPE-16)
Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-01-22
Bergfelt, A., Lacey, M. J., Hedman, J., Sångeland, C., Brandell, D. & Bowden, T. (2018). ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries: synthesis, electrochemical characterization and mechanical stabilization by block copolymerization. RSC Advances, 8(30), 16716-16725
Open this publication in new window or tab >>ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries: synthesis, electrochemical characterization and mechanical stabilization by block copolymerization
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2018 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 30, p. 16716-16725Article in journal (Refereed) Published
Abstract [en]

In this work, three types of polymers based on epsilon-caprolactone have been synthesized: poly(epsilon-caprolactone), polystyrene-poly(epsilon-caprolactone), and polystyrene-poly(epsilon-caprolactone-r-trimethylene carbonate) (SCT), where the polystyrene block was introduced to improve the electrochemical and mechanical performance of the material. Solid polymer electrolytes (SPEs) were produced by blending the polymers with 10-40 wt% lithium bis(trifluoromethane) sulfonimide (LiTFSI). Battery devices were thereafter constructed to evaluate the cycling performance. The best performing battery half-cell utilized an SPE consisting of SCT and 17 wt% LiTFSI as both binder and electrolyte; a Li vertical bar SPE vertical bar LiFePO4 cell that cycled at 40 degrees C gave a discharge capacity of about 140 mA h g(-1) at C/5 for 100 cycles, which was superior to the other investigated electrolytes. Dynamic mechanical analysis (DMA) showed that the storage modulus E' was about 5 MPa for this electrolyte.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:uu:diva-340854 (URN)10.1039/c8ra00377g (DOI)000431814500034 ()
Funder
Swedish Energy Agency, 42031-1EU, Horizon 2020, 685716
Available from: 2018-02-04 Created: 2018-02-04 Last updated: 2018-08-27Bibliographically approved
Lacey, M., Österlund, V., Bergfelt, A., Jeschull, F., Bowden, T. & Brandell, D. (2017). A robust, water-based, functional binder framework for high energy Li-S batteries. In: : . Paper presented at Lithium Sulfur Batteries: Mechanisms, Modelling and Materials.
Open this publication in new window or tab >>A robust, water-based, functional binder framework for high energy Li-S batteries
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2017 (English)Conference paper, Oral presentation only (Other academic)
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-338014 (URN)
Conference
Lithium Sulfur Batteries: Mechanisms, Modelling and Materials
Available from: 2018-01-06 Created: 2018-01-06 Last updated: 2018-01-06
Lacey, M., Österlund, V., Bergfelt, A., Jeschull, F., Bowden, T. & Brandell, D. (2017). A Robust, Water-Based, Functional Binder Framework for High-Energy Lithium-Sulfur Batteries. ChemSusChem, 10(13), 2758-2766
Open this publication in new window or tab >>A Robust, Water-Based, Functional Binder Framework for High-Energy Lithium-Sulfur Batteries
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2017 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 13, p. 2758-2766Article in journal (Refereed) Published
Abstract [en]

We report here a water-based functional binder framework for the lithium-sulfur battery systems, based on the general combination of a polyether and an amide-containing polymer. These binders are applied to positive electrodes optimised towards high-energy electrochemical performance based only on commercially available materials. Electrodes with up to 4 mAhcm(-2) capacity and 97-98% coulombic efficiency are achievable in electrodes with a 65% total sulfur content and a poly(ethylene oxide): poly(vinylpyrrolidone) (PEO: PVP) binder system. Exchange of either binder component for a different polymer with similar functionality preserves the high capacity and coulombic efficiency. The improvement in coulombic efficiency from the inclusion of the coordinating amide group was also observed in electrodes where pyrrolidone moieties were covalently grafted to the carbon black, indicating the role of this functionality in facilitating polysulfide adsorption to the electrode surface. The mechanical properties of the electrodes appear not to significantly influence sulfur utilisation or coulombic efficiency in the short term but rather determine retention of these properties over extended cycling. These results demonstrate the robustness of this very straightforward approach, as well as the considerable scope for designing binder materials with targeted properties.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-337672 (URN)10.1002/cssc.201700743 (DOI)000405080200009 ()28544635 (PubMedID)
Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2018-02-01Bibliographically approved
Bergfelt, A., Rubatat, L., Mogensen, R., Brandell, D. & Bowden, T. (2017). d8-poly(methyl methacrylate)-poly[(oligo ethylene glycol) methyl ether methacrylate] tri-block-copolymer electrolytes: Morphology, conductivity and battery performance. Polymer, 131, 234-242
Open this publication in new window or tab >>d8-poly(methyl methacrylate)-poly[(oligo ethylene glycol) methyl ether methacrylate] tri-block-copolymer electrolytes: Morphology, conductivity and battery performance
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2017 (English)In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 131, p. 234-242Article in journal (Refereed) Published
Abstract [en]

A series of deuterated tri-block copolymers with the general structure d(8)-PMMA-POEGMA-d(8)-PMMA, with variation in d(8)-PMMA chain length, were synthesized using sequential controlled radical polymerization (ATRP). Solid polymer electrolytes (SPEs) were produced by blending tri-block copolymers and lithium bis(trifluoro methylsulfonate) (LiTFSI). Small-angle neutron scattering (SANS) was used to study the bulk morphology of the deuterated tri-block copolymer electrolyte series at 25 degrees C, 60 degrees C and 95 degrees C. The lack of a second T-g in DSC analysis together with modelling with the random phase approximation model (RPA) confirmed that the electrolytes are in the mixed state, with negative Flory-Huggins interaction parameters. AC impedance spectroscopy was used to study the ionic conductivity of the SPE series in the temperature interval 30 degrees C-90 degrees C, and a battery device was constructed to evaluate a 25 wt% d(8)-PMMA electrolyte. The Li | SPE | LiFePO4 cell cycled at 60 degrees C, giving a discharge capacity of 120 mAh g(-1), while cyclic voltammetry showed that the SPE was stable at 60 degrees C.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:uu:diva-337667 (URN)10.1016/j.polymer.2017.10.044 (DOI)000415014300026 ()
Funder
Swedish Research Council
Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2018-02-22Bibliographically approved
Bergman, M., Bergfelt, A., Sun, B., Bowden, T., Brandell, D. & Johansson, P. (2015). Graft copolymer electrolytes for high temperature Li-battery applications, using poly(methyl methacrylate) grafted poly(ethylene glycol)methyl ether methacrylate and lithium bis(trifluoromethanesulfonimide). Electrochimica Acta, 175, 96-103
Open this publication in new window or tab >>Graft copolymer electrolytes for high temperature Li-battery applications, using poly(methyl methacrylate) grafted poly(ethylene glycol)methyl ether methacrylate and lithium bis(trifluoromethanesulfonimide)
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2015 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 175, p. 96-103Article in journal (Refereed) Published
Abstract [en]

For successful hybridization of heavy vehicles, high temperature batteries might be the solution. Here, high temperature solid polymer electrolytes (SPE's) based on different ratios of poly(methyl methacrylate) (PMMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA), with LiTFSI salt (at a fixed ether oxygen (EO):Li ratio of 20:1) have been prepared and investigated. The copolymers comprise PMMA backbones with grafted PEGMA side-chains containing 9 EO units. The SPE systems were characterized using Raman spectroscopy, broadband dielectric spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, and electrochemical cycling in prototype cells, with a particular focus on the 83 wt% PEGMA system. The electrolytes have good thermal stabilities and dissociate the LiTFSI salt easily, while at the same time maintaining low glass transition temperatures (T-g's). Depending on the polymeric structure, ionic conductivities >1 mS cm(-1) at 110 degrees C are detected, thus providing ion transport properties for a broad range of electrochemical applications. Prototype Li vertical bar polymer electrolyte vertical bar LiFePO4 cells utilizing the SPE at 60 degrees C showed surprisingly low capacities (<20 mA h g(-1) LiFePO4), which could be due to poor electrode/electrolyte contacts.

Keywords
Solid polymer electrolyte, High temperature battery, Poly(methyl methacrylate), Ether oxygen, LiTFSI
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-262959 (URN)10.1016/j.electacta.2015.01.226 (DOI)000360178600014 ()
Funder
Swedish Foundation for Strategic Research Swedish Research CouncilÅForsk (Ångpanneföreningen's Foundation for Research and Development)
Available from: 2015-09-29 Created: 2015-09-23 Last updated: 2017-12-01Bibliographically approved
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